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Interesting, Jeff !

12V sucked from 48V, without an inverter ! Thumbs up !

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In your intended setup of your battery banks, do you use 1 common BMS, or 1 on each (48V) battery ?

How about redundancy, if a common BMS fails ? (= no power at all.)

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Another thing, how about making the motor wattage output adjustable, so it is possible to use eg. 96V for a burst mode ? Many 48V motors can be powered by 96V (or higher).

I assume that the wiring can handle that. Making two sets of banks 48V, to be serial connected to 96V.

The short "event" should of course be managed by the BMS/power management system.

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i'm wondering if this new Li-battery technology is becoming a little too advanced for sailing now...

Safety first, when out on the water, right ? We can't just park the boat at the curb and call a cab when out on the blue.

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To be true, things made in China is not my cup of tea, but in these days, unfortunately simply unavoidable !

I was a supervisor in China for several years, and know how they make things, and all of QC is not like in the West.

Buy a ME1616 electromotor. Made in China, then sold in the West.

Buy yourself a german or US car. Half of the smaller parts in it are made in China by now.

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Company supervisors are not in China now, because of the Made in China virus.

Who wants to spend 2-4 weeks in quarantine to go for an inspection ??

Who's checking the quality now ?

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However, I believe that new, checked, LiFePO4 batteries will last my sailing life out, but the electronics is another concern.

Especially in a marine environment (humid and salty).

Can you provide recommendations where to setup these (rather large) electronic regulators/inverters/BMS'es in the boat ?

I guess IP rating is not relevant, if not encapsuled in IP-rated boxes.

If put into boxes, then there's a cooling issue...

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Working hard on the ultimate solution for my own EMS/Y system conversion design.

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Cheers, guys

Carsten

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Hint : EMS/Y = Electric Motor Sailing Yacht ;-)

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On Friday, 30 April 2021, 02:46:25 GMT+8, Jeff LaCoursiere <jeff@...> wrote:

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We haven't had any bad cells imported yet, knock wood.? We *are* doing our best to burn down our offices with our BMS experiments though :)? Also, our latest batch was all EVE 280AH cells, the Lishen 272AH are apparently "all gone".

Another cool idea we are kicking around... we want our 48v pack to have a 12v tap, so you can use it as your house battery as well as your traction battery.? I'm disappointed in the available downconverters, mostly current limited to 30-60A.? Maybe that would be enough for your house, but it wouldn't do it for mine.

So we want to try to cycle through internal banks of four cells, very quickly (like 10khz), connecting them in turn to the 12v tap.? We believe that this way you will be able to pull the full 1C discharge of the 16 cell pack (280A), but at 12v!? We hope to maintain balance in discharge by cycling very fast, but the BMS should pick up the slack.

Cheers,

Jeff LaCoursiere
s/v Angels Quest

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